• Fibers and Polymers
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• 제1권1호
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• pp.18-24
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• 2000

The phase transformation of poly(trimethylene terephthalate) in crystalline state was simulated by atomistic modeling using molecular mechanics technique. The crystalline structure of PTT was successfully prepared using the well-defined unit cell structure of PTT and was satisfactorily verified by comparing that with the structure obtained from the x-ray diffraction experiments. The basic elastic properties were predicted in this study, showing that the crystalline structure of PTT is very pliable to the deformation at small strain. When the crystalline structure of PTT was stepwise deformed up to 50% of strain in chain direction under uniaxial extension condition, the change in dihedral angle of trimethylene unit from gg to tt conformation was accompanied with a large increase of stress, indicating that the phase transformation of PTT in crystalline state is difficult to occur.

• Carbon letters
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• 제14권4호
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• pp.243-246
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• 2013

In this work, electroless Ni-plating on polyethylene terephthalate (PET) ultra-fine fibers surfaces was carried out to improve the electric conductivity of the fiber. The surface properties of PET ultra-fine fibers were characterized using scanning electron microscopy, X-ray diffraction, and contact angle analyses. The electric conductivity of the fibers was measured using a 4-point testing method. The experimental results revealed the presence of island-like nickel clusters on the PET ultra-fine fibers surfaces in the initial plating state, and the electric conductivity of the Ni-plated fibers was enhanced with increasing plating time and thickness of the Ni-layers on the PET ultra-fine fibers.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.456-461
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• 2001

This paper depicts the weak shock wave propagating inside some kinds of pipe bends. Computational work is to solve the two-dimensional, compressible, unsteady Euler Equations. The second-order TVD scheme is employed to discretize the governing equations. For the computations, the incident normal shock wave is assumed at the entrance of the pipe bend, and its Mach number is changed between 1.1 and 1.7. The turning angle and radius of the curvature of the pipe bend are changed to investigate the effects on the shock wave structure. The present computational results clearly show the shock wave reflection and diffraction occurring in the pipe bend. In particular, the vortex generation, which occurs at the edge of the bend, and its shedding mechanism are discussed in details.

• 전자공학회논문지D
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• 제35D권2호
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• pp.70-77
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• 1998

An aerial image simulator for the synchroton X-ray proximity lithography system has been developed. The modal expansion method and Rayleigh-Sommerfeld diffraction theory are used in calculating the aerial image which is formed by diffracting of the partially coherent X-ray, Experimental results of PALC(POSTECH Advanced Lithography Center) lighography system and simulated results are compared. The experimental and theoretical values of the width of replicated lines are consisted with the relative error less than ~5%. The method to determine the divergent angle of X-ray from the analysis of the width of replicated lines is given.

• Applied Microscopy
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• 제24권4호
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• pp.115-122
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• 1994

A computer program has been developed to analyze easily the Kikuchi pattern which is useful in obtaining the crystallographic data of materials. This program can simulate the Kikuchi patterns for 14 Bravais lattice by using the matrix algebra. Convenient menu system was also added to enhance the applications of the program. That is, by varying the tilting angle, camera length (RADIUS) and $S_{max}$ in the menu, various Kikuchi patterns can be obtained. The simulated patterns, then, can be compared with the experimentally-obtained Kikuchi pattern to examine validity of simulation.

• 전자공학회논문지A
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• 제29A권4호
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• pp.14-21
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• 1992

An optical novelty filter is implemented using photorefractive materal(BaTiO$_{3}$) as a recording materal and commercial liquid crystal TV as a spatial light polarization modulator. If a signal beam incident at the proper, the loop and the crossing angle inside th e crystal is formed to get maximum diffraction efficiency and BaTiO$_{3}$ as a self-pumped phase conjugation mirror show that phase conjugate reflectivity was 20 times as much as ordinary polarization if signal beam is extraordinary. In this paper, the stoke's theorem which is a reciprocal theorem for which is a reciprocal theorem for beam path is experimentally proved, and good output images were obtained with optical experiment of novelty filter which is formed by use of Michelson interferometer.

• 대한전자공학회논문지SD
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• 제42권9호
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• pp.19-28
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• 2005

특정한 각으로 입사하는 가간섭인 평행광선들에 의한 간섭무뉘는 1차원 정보로서 표현되는 회절격자와 흡사한 홀로그램을 구성하며, 이러한 홀로그램을 1차원 홀로그램이라 제안한다. 1차원 홀로그램을 이용하여 표시장치의 구성이 가능하며, 간단한 광 컴퓨팅구조로서 빠르게 간섭무늬를 계산할 수 있다. 이러한 표시장치를 구성하는 방법을 제시한다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.71-71
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• 2010

Copper oxide thin films were deposited on the p-type Si(100) by r.f. magnetron sputtering as a function of different substrate temperature. The deposited copper oxide thin films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), spectroscopic ellipsometry (SE), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The SEM and SE data show that the thickness of the copper oxide films was about 170 nm. AFM images show that the surface roughness of copper oxide films was increased with increasing substrate temperature. As the substrate temperature increased, monoclinic CuO (111) peak appeared and the crystal size decreased while the monoclinic CuO (-111) peak was independent on the substrate temperature. The oxidation states of Cu 2p and O 1s resulted from XPS were not affected on the substrate temperature. The contact angle measurement was also studied and indicated that the surface of copper oxide thin films deposited high temperature has more hydrophobic surface than that of deposited at low temperature.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.209.2-209.2
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• 2014

In recent years, researches about hydrophobic and hydrophilic surfaces have been executed however their other effects have not been researched enough. In this paper, the fabrication method of hierarchical structures of micro line array combined with fluorinated wax for anisotropic superomniphobic wettability is presented. We have achieved anisotropic and superomniphobic surface via simple two step methods, which are maskless photolithography and wax deposition. In order to prove how to provide those characteristics, SEM, contact angle measurement tool and X-ray diffraction are used. Fluorinated wax is crystalized self-assembly and it is subordinated on micro line array so that it is able to display anisotropic wettability. Understanding on anisotropic superomniphobic surface and simple fabrication method has been attracted to apply for lots of applications which range from self-cleaning surface, microfluidic chip, to directionally fluid control device, even in oily fluid.

• 한국레이저가공학회지
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• 제2권2호
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• pp.27-33
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• 1999

Electron beam was applied on the low carbon steel in order to fabricate Metal/Metal GBM(Graded Boundary Material). Ni sheet was placed on the steel substrate. The electron beam was irradiated on the surface and produced a homogeous alloyed layer. Sequential repetition of electron beam treatments for 4 times resulted in 8mm thick graded layer. To determine each layers property, optical microscopy, XRD, microhardness tester and EDS were used. The residual stress was measured by the low angle x-ray diffraction method. The graded boundary layer was stepwise profile, but Ni content incresed up to 80 wt% and Fe content decreased 20 wt% near surface. Each layers microstructure and hardness varied by different Fe/Ni composition. The compressive residual stress was induced by martensite transformation in the 1st and End layers and the shrinkage cracks were formed in graded layer by rapid cooling.